at+own(one) - he realised his mistake 'at' his 'own' and wanted to make amends for it..
remember in the movie "king" brahmanandam scolds trisha AH TONE enti,later he AMENDS his words after nagarjuna beats him up! !!!!!!!!!!!!!!!!!!! don't give mnemonics using stupid tamil (or what so ever those may be ) movies !!
atone ~ at stone; imagine someone throws a stone on (at)someone else and then realizes his mistake. So, he atones.
When u use harsh words for ur girl ,later u REPENT for that before her with A TONE that sounds pleasing
He ATTAINED moxa by leaving his sins
AT-ON(c)E, your boyfriend is ready to "pay for" you. Also, AT-ON(c)E, u realize your mistakes & "make amendments for" it.
at+one(once) he realized his mistake n wanted to ammend for the same
One puts all the blames AT ONE